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Séminaire Laurent BACRI - 24/4/2015

Vendredi 24 avril 2015 - 10h30 - Salle de conférences


Sensing proteins, polyelectrolytes and polymers by nanopores


Docteur Laurent BACRI LAMBE CNRS
Universités d’Evry et de Cergy-Pontoise


Abstract :
We study effects of applied voltage, electro-osmotic flow (EOF) and osmotic pressure to control the driving force of macromolecules inside nanopores. We observe that the dynamics of polyelectrolytes or proteins are controlled by electrical force. The entry of these molecules follows a Van’t Hoff law as a function of the applied voltage. The energy barrier has the magnitude of few kBT and depends on the nanopore type (size, net charge, structure, geometry) and interactions between the macromolecules and pore surface. We show at low voltages, that the dwell time decreases exponentially with the electric force, showing an energy barrier behavior. At high voltage, this time is inversely proportional to the applied voltage, then the dynamics is governed by the electrophoresis.

About purely neutral macromolecules, the transport cannot be controlled directly by the applied voltage. Nevertheless, we modulate the driving force by using the flow of the counter ions through the nanopore, allowing the confinement of neutral nano-objects as PEG or beta-cyclodextrins. The strength of EOF depends on the applied voltage, salt concentration, nature of the cations. Interestingly, the dynamics of high concentrated polymers solutions could be controlled by the osmotic pressure, showing reptation behavior according to de Gennes’ theory.